Add support for agentx to smtpd.

This is based around NETWORK-SERVICES-MIB from RFC2788 and MTA-MIB from
RFC2789, but does not export the full spec. Hopefully this will expand in
the future.

People who want to use this against net-snmp (currently the only option
known to me at the time of writing) may want to add -I -mta_sendmail to the
flags, so net-snmp doesn't throw garbage into the mib-2.28 subtree.

7 files changed, 420 insertions, 13 deletions

diff --git a/usr.sbin/smtpd/control.c b/usr.sbin/smtpd/control.c
index 0e35bbd1..7ec7b264 100644
--- a/usr.sbin/smtpd/control.c
+++ b/usr.sbin/smtpd/control.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: control.c,v 1.123 2018/05/31 21:06:12 gilles Exp $	*/
+/*	$OpenBSD: control.c,v 1.124 2020/09/23 18:01:26 martijn Exp $	*/
 
 /*
  * Copyright (c) 2012 Gilles Chehade <gilles@poolp.org>
@@ -76,7 +76,7 @@ extern const char *backend_stat;
 static uint64_t			connid = 0;
 static struct tree		ctl_conns;
 static struct tree		ctl_count;
-static struct stat_digest	digest;
+struct stat_digest		digest;
 
 #define	CONTROL_FD_RESERVE		5
 #define	CONTROL_MAXCONN_PER_CLIENT	32
@@ -160,6 +160,9 @@ control_imsg(struct mproc *p, struct imsg *imsg)
 		if (stat_backend)
 			stat_backend->set(key, &val);
 		return;
+	case IMSG_AGENTX_GETFD:
+		control_agentx_connect(imsg->fd);
+		return;
 	}
 
 	errx(1, "control_imsg: unexpected %s imsg",
@@ -257,6 +260,9 @@ control(void)
 	control_listen();
 
 #if HAVE_PLEDGE
+	if (env->sc_agentx != NULL)
+		control_agentx();
+
 	if (pledge("stdio unix recvfd sendfd", NULL) == -1)
 		err(1, "pledge");
 #endif
diff --git a/usr.sbin/smtpd/control_agentx.c b/usr.sbin/smtpd/control_agentx.c
new file mode 100644
index 00000000..4db3dd74
--- /dev/null
+++ b/usr.sbin/smtpd/control_agentx.c
@@ -0,0 +1,235 @@
+/*	$OpenBSD: control_agentx.c,v 1.1 2020/09/23 18:01:26 martijn Exp $ */
+
+/*
+ * Copyright (c) 2020 Martijn van Duren <martijn@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/queue.h>
+#include <sys/socket.h>
+#include <sys/tree.h>
+#include <sys/uio.h>
+
+#include <errno.h>
+#include <event.h>
+#include <imsg.h>
+#include <limits.h>
+#include <stdio.h>
+#include <subagentx.h>
+
+#include "log.h"
+#include "smtpd.h"
+
+static void control_agentx_nofd(struct subagentx *, void *, int);
+static void control_agentx_tryconnect(int, short, void *);
+static void control_agentx_read(int, short, void *);
+static void control_agentx_appltable(struct subagentx_varbind *);
+static void control_agentx_mtatable(struct subagentx_varbind *);
+
+static struct subagentx *sa;
+static struct subagentx_session *sas;
+static struct subagentx_context *sac;
+static struct subagentx_region *application, *mta;
+static struct subagentx_index *applIndex;
+static struct subagentx_object *applName, *applDirectoryName;
+static struct subagentx_object *applVersion, *applUptime, *applOperStatus;
+static struct subagentx_object *applDescription, *applURL;
+static struct subagentx_object *mtaReceivedMessages, *mtaStoredMessages;
+static struct subagentx_object *mtaTransmittedMessages, *mtaLoopsDetected;
+static struct event connev, rev;
+
+extern struct stat_digest digest;
+
+#define APPLICATION SUBAGENTX_MIB2, 27
+#define APPLTABLE APPLICATION, 1
+#define APPLENTRY APPLTABLE, 1
+#define APPLINDEX APPLENTRY, 1
+#define APPLNAME APPLENTRY, 2
+#define APPLDIRECTORYNAME APPLENTRY, 3
+#define APPLVERSION APPLENTRY, 4
+#define APPLUPTIME APPLENTRY, 5
+#define APPLOPERSTATUS APPLENTRY, 6
+#define APPLLASTCHANGE APPLENTRY, 7
+#define APPLDESCRIPTION APPLENTRY, 16
+#define APPLURL APPLENTRY, 17
+#define MTA SUBAGENTX_MIB2, 28
+#define MTATABLE MTA, 1
+#define MTAENTRY MTATABLE, 1
+#define MTARECEIVEDMESSAGES MTAENTRY, 1
+#define MTASTOREDMESSAGES MTAENTRY, 2
+#define MTATRANSMITTEDMESSAGES MTAENTRY, 3
+#define MTALOOPSDETECTED MTAENTRY, 12
+
+#define APPLOPERSTATUS_UP 1
+#define APPLOPERSTATUS_DOWN 2
+#define APPLOPERSTATUS_HALTED 3
+#define APPLOPERSTATUS_CONGESTED 4
+#define APPLOPERSTATUS_RESTARTING 5
+#define APPLOPERSTATUS_QUIESCING 6
+
+void
+control_agentx(void)
+{
+	subagentx_log_fatal = fatalx;
+	subagentx_log_warn = log_warnx;
+	subagentx_log_info = log_info;
+	subagentx_log_debug = log_debug;
+
+	if ((sa = subagentx(control_agentx_nofd, NULL)) == NULL)
+		fatal("subagentx");
+	if ((sas = subagentx_session(sa, NULL, 0, "OpenSMTPd", 0)) == NULL)
+		fatal("subagentx_session");
+	if ((sac = subagentx_context(sas, env->sc_agentx->context)) == NULL)
+		fatal("subagentx_context");
+
+        if ((application = subagentx_region(sac,
+	    SUBAGENTX_OID(APPLICATION), 0)) == NULL ||
+            (mta = subagentx_region(sac, SUBAGENTX_OID(MTA), 0)) == NULL)
+                fatal("subagentx_region");
+	switch (env->sc_agentx->applIndexType) {
+	case AGENTX_INDEX_TYPE_ANY:
+		if ((applIndex = subagentx_index_integer_any(application,
+		    SUBAGENTX_OID(APPLINDEX))) == NULL)
+			fatal("subagentx_index_integer_any");
+		break;
+	case AGENTX_INDEX_TYPE_NEW:
+		if ((applIndex = subagentx_index_integer_new(application,
+		    SUBAGENTX_OID(APPLINDEX))) == NULL)
+			fatal("subagentx_index_integer_new");
+		break;
+	case AGENTX_INDEX_TYPE_VALUE:
+		if ((applIndex = subagentx_index_integer_value(application,
+		    SUBAGENTX_OID(APPLINDEX),
+		    env->sc_agentx->applIndex)) == NULL)
+			fatal("subagentx_index_integer_value");
+		break;
+	case AGENTX_INDEX_TYPE_UNDEFINED:
+		fatalx("%s: How did I get here?", __func__);
+	}
+
+        if ((applName = subagentx_object(application, SUBAGENTX_OID(APPLNAME),
+	    &applIndex, 1, 0, control_agentx_appltable)) == NULL ||
+            (applDirectoryName = subagentx_object(application,
+            SUBAGENTX_OID(APPLDIRECTORYNAME), &applIndex, 1,
+            0, control_agentx_appltable)) == NULL ||
+            (applVersion = subagentx_object(application,
+            SUBAGENTX_OID(APPLVERSION), &applIndex, 1,
+            0, control_agentx_appltable)) == NULL ||
+            (applUptime = subagentx_object(application,
+            SUBAGENTX_OID(APPLUPTIME), &applIndex, 1,
+            0, control_agentx_appltable)) == NULL ||
+            (applOperStatus = subagentx_object(application,
+            SUBAGENTX_OID(APPLOPERSTATUS), &applIndex, 1,
+            0, control_agentx_appltable)) == NULL ||
+            (applDescription = subagentx_object(application,
+            SUBAGENTX_OID(APPLDESCRIPTION), &applIndex, 1,
+            0, control_agentx_appltable)) == NULL ||
+            (applURL = subagentx_object(application, SUBAGENTX_OID(APPLURL),
+	    &applIndex, 1, 0, control_agentx_appltable)) == NULL ||
+	    (mtaReceivedMessages = subagentx_object(mta,
+            SUBAGENTX_OID(MTARECEIVEDMESSAGES), &applIndex, 1,
+            0, control_agentx_mtatable)) == NULL ||
+	    (mtaStoredMessages = subagentx_object(mta,
+            SUBAGENTX_OID(MTASTOREDMESSAGES), &applIndex, 1,
+            0, control_agentx_mtatable)) == NULL ||
+	    (mtaTransmittedMessages = subagentx_object(mta,
+            SUBAGENTX_OID(MTATRANSMITTEDMESSAGES), &applIndex, 1,
+            0, control_agentx_mtatable)) == NULL ||
+	    (mtaLoopsDetected = subagentx_object(mta,
+            SUBAGENTX_OID(MTALOOPSDETECTED), &applIndex, 1,
+            0, control_agentx_mtatable)) == NULL)
+                fatal("subagentx_object");
+	
+}
+
+static void
+control_agentx_nofd(struct subagentx *unused, void *cookie, int close)
+{
+	event_del(&rev);
+	control_agentx_tryconnect(-1, 0, NULL);
+}
+
+static void
+control_agentx_tryconnect(int fd, short event, void *cookie)
+{
+	m_create(p_parent, IMSG_AGENTX_GETFD, 0, 0, -1);
+	m_close(p_parent);
+}
+
+static void
+control_agentx_read(int fd, short event, void *cookie)
+{
+	subagentx_read(sa);
+}
+
+void
+control_agentx_connect(int fd)
+{
+	struct timeval timeout = {3, 0};
+
+	if (fd == -1) {
+		evtimer_set(&connev, control_agentx_tryconnect, NULL);
+		evtimer_add(&connev, &timeout);
+		return;
+	}
+
+	subagentx_connect(sa, fd);
+
+	event_set(&rev, fd, EV_READ|EV_PERSIST, control_agentx_read, NULL);
+	event_add(&rev, NULL);
+}
+
+static void
+control_agentx_appltable(struct subagentx_varbind *vb)
+{
+	if (subagentx_varbind_get_object(vb) == applName)
+		subagentx_varbind_string(vb, "OpenSMTPd");
+	else if (subagentx_varbind_get_object(vb) == applDirectoryName)
+		subagentx_varbind_string(vb, "");
+	else if (subagentx_varbind_get_object(vb) == applVersion)
+		subagentx_varbind_string(vb, SMTPD_VERSION);
+	else if (subagentx_varbind_get_object(vb) == applUptime)
+		subagentx_varbind_timeticks(vb,
+		    (uint32_t) ((time(NULL) - digest.startup) * 100));
+	else if (subagentx_varbind_get_object(vb) == applOperStatus)
+		subagentx_varbind_integer(vb,
+		    env->sc_flags & SMTPD_SMTP_PAUSED ?
+		    APPLOPERSTATUS_DOWN : APPLOPERSTATUS_UP);
+	else if (subagentx_varbind_get_object(vb) == applDescription)
+		subagentx_varbind_string(vb, "OpenSMTPD is a FREE "
+		    "implementation of the server-side SMTP protocol as "
+		    "defined by RFC 5321, with some additional standard "
+		    "extensions. It allows ordinary machines to exchange "
+		    "emails with other systems speaking the SMTP protocol.");
+	else if (subagentx_varbind_get_object(vb) == applURL)
+		subagentx_varbind_string(vb, "");
+	else
+		fatalx("%s: unexpected callback", __func__);
+}
+
+static void
+control_agentx_mtatable(struct subagentx_varbind *vb)
+{
+	if (subagentx_varbind_get_object(vb) == mtaReceivedMessages)
+		subagentx_varbind_counter32(vb, (uint32_t) digest.evp_enqueued);
+	else if (subagentx_varbind_get_object(vb) == mtaStoredMessages)
+		subagentx_varbind_counter32(vb,
+		    (uint32_t) (digest.evp_enqueued - digest.evp_dequeued));
+	else if (subagentx_varbind_get_object(vb) == mtaTransmittedMessages)
+		subagentx_varbind_counter32(vb, digest.evp_dequeued);
+	else if (subagentx_varbind_get_object(vb) == mtaLoopsDetected)
+		subagentx_varbind_counter32(vb, digest.dlv_loop);
+	else
+		fatalx("%s: unexpected callback", __func__);
+}
diff --git a/usr.sbin/smtpd/parse.y b/usr.sbin/smtpd/parse.y
index a4afed97..679a53f8 100644
--- a/usr.sbin/smtpd/parse.y
+++ b/usr.sbin/smtpd/parse.y
@@ -1,4 +1,4 @@
-/*	$OpenBSD: parse.y,v 1.279 2020/09/16 11:19:42 martijn Exp $	*/
+/*	$OpenBSD: parse.y,v 1.280 2020/09/23 18:01:26 martijn Exp $	*/
 
 /*
  * Copyright (c) 2008 Gilles Chehade <gilles@poolp.org>
@@ -31,6 +31,7 @@
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/ioctl.h>
+#include <sys/un.h>
 
 #include <net/if.h>
 #include <netinet/in.h>
@@ -51,6 +52,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <subagentx.h>
 #include <syslog.h>
 #include <unistd.h>
 #ifdef HAVE_UTIL_H
@@ -179,9 +181,9 @@ typedef struct {
 
 %}
 
-%token	ACTION ADMD ALIAS ANY ARROW AUTH AUTH_OPTIONAL
+%token	ACTION ADMD AGENTX ALIAS ANY APPLINDEX ARROW AUTH AUTH_OPTIONAL
 %token	BACKUP BOUNCE BYPASS
-%token	CA CERT CHAIN CHROOT CIPHERS COMMIT COMPRESSION CONNECT
+%token	CA CERT CHAIN CHROOT CIPHERS COMMIT COMPRESSION CONNECT CONTEXT
 %token	DATA DATA_LINE DHE DISCONNECT DOMAIN
 %token	EHLO ENABLE ENCRYPTION ERROR EXPAND_ONLY 
 %token	FCRDNS FILTER FOR FORWARD_ONLY FROM
@@ -194,7 +196,7 @@ typedef struct {
 %token	MAIL_FROM MAILDIR MASK_SRC MASQUERADE MATCH MAX_MESSAGE_SIZE MAX_DEFERRED MBOX MDA MTA MX
 %token	NO_DSN NO_VERIFY NOOP
 %token	ON
-%token	PHASE PKI PORT PROC PROC_EXEC PROXY_V2
+%token	PATH PHASE PKI PORT PROC PROC_EXEC PROXY_V2
 %token	QUEUE QUIT
 %token	RCPT_TO RDNS RECIPIENT RECEIVEDAUTH REGEX RELAY REJECT REPORT REWRITE RSET
 %token	SCHEDULER SENDER SENDERS SMTP SMTP_IN SMTP_OUT SMTPS SOCKET SRC SRS SUB_ADDR_DELIM
@@ -230,6 +232,7 @@ grammar		: /* empty */
 		| grammar dispatcher '\n'
 		| grammar match '\n'
 		| grammar filter '\n'
+		| grammar agentx '\n'
 		| grammar error '\n'		{ file->errors++; }
 		;
 
@@ -1964,6 +1967,82 @@ FILTER STRING CHAIN {
 }
 ;
 
+agentxopt	:
+CONTEXT STRING {
+	if (conf->sc_agentx->context != NULL) {
+		yyerror("redefinition of agentx context");
+		free($2);
+		YYERROR;
+	}
+	conf->sc_agentx->context = $2;
+}
+| PATH STRING {
+	if (strlen($2) >= sizeof(((struct sockaddr_un *)0)->sun_path)) {
+		yyerror("agentx path too large");
+		free($2);
+		YYERROR;
+	}
+	if ($2[0] != '/') {
+		yyerror("agentx path must be absolute");
+		free($2);
+		YYERROR;
+	}
+	if (conf->sc_agentx->path != NULL) {
+		yyerror("redefinition of agentx path");
+		free($2);
+		YYERROR;
+	}
+	conf->sc_agentx->path = $2;
+}
+| APPLINDEX STRING {
+	if (conf->sc_agentx->applIndexType != AGENTX_INDEX_TYPE_UNDEFINED) {
+		yyerror("redefinition of agentx applIndex");
+		YYERROR;
+	}
+
+	if (strcasecmp($2, "any") == 0)
+		conf->sc_agentx->applIndexType = AGENTX_INDEX_TYPE_ANY;
+	else if (strcasecmp($2, "new") == 0)
+		conf->sc_agentx->applIndexType = AGENTX_INDEX_TYPE_NEW;
+	else {
+		yyerror("invalid applIndex");
+		YYERROR;
+	}
+}
+| APPLINDEX NUMBER {
+	if (conf->sc_agentx->applIndexType != AGENTX_INDEX_TYPE_UNDEFINED) {
+		yyerror("redefinition of agentx applIndex");
+		YYERROR;
+	}
+	if ($2 > UINT32_MAX) {
+		yyerror("agentx applIndex too large");
+		YYERROR;
+	}
+	if ($2 < 1) {
+		yyerror("agentx applIndex too small");
+		YYERROR;
+	}
+
+	conf->sc_agentx->applIndexType = AGENTX_INDEX_TYPE_VALUE;
+	conf->sc_agentx->applIndex = (uint32_t) $2;
+}
+;
+
+agentxopts	: /* empty */
+		| agentxopts agentxopt
+		;
+
+agentx:
+AGENTX {
+	conf->sc_agentx = xcalloc(1, sizeof(*conf->sc_agentx));
+} agentxopts {
+	if (conf->sc_agentx->path == NULL)
+		conf->sc_agentx->path = SUBAGENTX_AGENTX_MASTER;
+	if (conf->sc_agentx->applIndexType == AGENTX_INDEX_TYPE_UNDEFINED)
+		conf->sc_agentx->applIndexType = AGENTX_INDEX_TYPE_ANY;
+}
+;
+
 size		: NUMBER		{
 			if ($1 < 0) {
 				yyerror("invalid size: %" PRId64, $1);
@@ -2624,8 +2703,10 @@ lookup(char *s)
 	static const struct keywords keywords[] = {
 		{ "action",		ACTION },
 		{ "admd",		ADMD },
+		{ "agentx",		AGENTX },
 		{ "alias",		ALIAS },
 		{ "any",		ANY },
+		{ "applIndex",		APPLINDEX },
 		{ "auth",		AUTH },
 		{ "auth-optional",     	AUTH_OPTIONAL },
 		{ "backup",		BACKUP },
@@ -2639,6 +2720,7 @@ lookup(char *s)
 		{ "commit",		COMMIT },
 		{ "compression",	COMPRESSION },
 		{ "connect",		CONNECT },
+		{ "context",		CONTEXT },
 		{ "data",		DATA },
 		{ "data-line",		DATA_LINE },
 		{ "dhe",		DHE },
@@ -2682,6 +2764,7 @@ lookup(char *s)
 		{ "no-verify",		NO_VERIFY },
 		{ "noop",		NOOP },
 		{ "on",			ON },
+		{ "path",		PATH },
 		{ "phase",		PHASE },
 		{ "pki",		PKI },
 		{ "port",		PORT },
diff --git a/usr.sbin/smtpd/smtpd.c b/usr.sbin/smtpd/smtpd.c
index f18b1446..240e688b 100644
--- a/usr.sbin/smtpd/smtpd.c
+++ b/usr.sbin/smtpd/smtpd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: smtpd.c,v 1.333 2020/05/06 16:03:30 millert Exp $	*/
+/*	$OpenBSD: smtpd.c,v 1.334 2020/09/23 18:01:27 martijn Exp $	*/
 
 /*
  * Copyright (c) 2008 Gilles Chehade <gilles@poolp.org>
@@ -28,6 +28,7 @@
 #include <sys/wait.h>
 #include <sys/stat.h>
 #include <sys/uio.h>
+#include <sys/un.h>
 #include <sys/mman.h>
 
 #ifdef BSD_AUTH
@@ -86,6 +87,7 @@
 #include "smtpd.h"
 #include "log.h"
 #include "ssl.h"
+#include "subagentx.h"
 
 extern char *__progname;
 
@@ -100,6 +102,7 @@ static void parent_send_config_lka(void);
 static void parent_send_config_pony(void);
 static void parent_send_config_ca(void);
 static void parent_sig_handler(int, short, void *);
+static int parent_open_agentx(void);
 static void forkmda(struct mproc *, uint64_t, struct deliver *);
 static int parent_forward_open(char *, char *, uid_t, gid_t);
 static struct child *child_add(pid_t, int, const char *);
@@ -302,6 +305,12 @@ parent_imsg(struct mproc *p, struct imsg *imsg)
 		m_add_string(p_lka, procname);
 		m_close(p_lka);
 		return;
+	case IMSG_AGENTX_GETFD:
+		fd = parent_open_agentx();
+
+		m_create(p_control, IMSG_AGENTX_GETFD, 0, 0, fd);
+		m_close(p_control);
+		return;
 	}
 
 	errx(1, "parent_imsg: unexpected %s imsg from %s",
@@ -508,6 +517,25 @@ parent_sig_handler(int sig, short event, void *p)
 	}
 }
 
+static int
+parent_open_agentx(void)
+{
+	int fd;
+	struct sockaddr_un sun;
+
+	sun.sun_len = sizeof(sun);
+	sun.sun_family = AF_UNIX;
+	strlcpy(sun.sun_path, env->sc_agentx->path, sizeof(sun.sun_path));
+
+	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1 ||
+	    connect(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
+		log_warn("agentx connect");
+		close(fd);
+		return -1;
+	}
+	return fd;
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -2185,6 +2213,8 @@ imsg_to_str(int type)
 	CASE(IMSG_CA_RSA_PRIVENC);
 	CASE(IMSG_CA_RSA_PRIVDEC);
 	CASE(IMSG_CA_ECDSA_SIGN);
+
+	CASE(IMSG_AGENTX_GETFD);
 	default:
 		(void)snprintf(buf, sizeof(buf), "IMSG_??? (%d)", type);
 
diff --git a/usr.sbin/smtpd/smtpd.conf.5 b/usr.sbin/smtpd/smtpd.conf.5
index d117b3c4..02d6ece4 100644
--- a/usr.sbin/smtpd/smtpd.conf.5
+++ b/usr.sbin/smtpd/smtpd.conf.5
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: smtpd.conf.5,v 1.253 2020/09/16 11:19:42 martijn Exp $
+.\"	$OpenBSD: smtpd.conf.5,v 1.254 2020/09/23 18:01:27 martijn Exp $
 .\"
 .\" Copyright (c) 2008 Janne Johansson <jj@openbsd.org>
 .\" Copyright (c) 2009 Jacek Masiulaniec <jacekm@dobremiasto.net>
@@ -17,7 +17,7 @@
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
 .\"
-.Dd $Mdocdate: September 16 2020 $
+.Dd $Mdocdate: September 23 2020 $
 .Dt SMTPD.CONF 5
 .Os
 .Sh NAME
@@ -326,6 +326,33 @@ The Administrative Management Domain this mailserver belongs to.
 The authservid will be forwarded to filters using it to identify or mark
 authentication-results headers.
 If omitted it defaults to the server name.
+.It Ic agentx Oo Cm applIndex Ar index Oc Oo Cm context Ar context Oc Op Cm path Ar path
+Export NETWORK-SERVICES-MIB and MTA-MIB metrics via an agentx compatible
+.Pq snmp
+daemon by connecting to
+.Ar path .
+Metrics can be found under the application subtree
+.Pq mib-2.27
+and mta subtree
+.Pq mib-2.28 .
+The index in the applTable and mtaTable can be controlled via
+.Cm applIndex .
+For the first available index it can be set to
+.Cm any ,
+for a new unused entry it can be set to
+.Cm new ,
+and if a fixed position is desired it can be set to a number between 1 and
+4294967295.
+If an index collision occurs because of a fixed position the metrics will not be
+exported.
+The default is
+.Cm any .
+If
+.Ar path
+is omitted it will default to
+.Pa /var/agentx/master .
+.Ar Context
+is the SNMPv3 context and can usually be omitted.
 .It Ic bounce Cm warn-interval Ar delay Op , Ar delay ...
 Send warning messages to the envelope sender when temporary delivery
 failures cause a message to remain on the queue for longer than
diff --git a/usr.sbin/smtpd/smtpd.h b/usr.sbin/smtpd/smtpd.h
index 237700c5..fc9707b5 100644
--- a/usr.sbin/smtpd/smtpd.h
+++ b/usr.sbin/smtpd/smtpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: smtpd.h,v 1.657 2020/09/16 11:19:42 martijn Exp $	*/
+/*	$OpenBSD: smtpd.h,v 1.658 2020/09/23 18:01:27 martijn Exp $	*/
 
 /*
  * Copyright (c) 2008 Gilles Chehade <gilles@poolp.org>
@@ -189,7 +189,7 @@ union lookup {
  * Bump IMSG_VERSION whenever a change is made to enum imsg_type.
  * This will ensure that we can never use a wrong version of smtpctl with smtpd.
  */
-#define	IMSG_VERSION		16
+#define	IMSG_VERSION		17
 
 enum imsg_type {
 	IMSG_NONE,
@@ -363,6 +363,8 @@ enum imsg_type {
 	IMSG_CA_RSA_PRIVENC,
 	IMSG_CA_RSA_PRIVDEC,
 	IMSG_CA_ECDSA_SIGN,
+
+	IMSG_AGENTX_GETFD,
 };
 
 enum smtp_proc_type {
@@ -652,6 +654,8 @@ struct smtpd {
 	int				        sc_srs_ttl;
 
 	char				       *sc_admd;
+
+	struct smtp_agentx		       *sc_agentx;
 };
 
 #define	TRACE_DEBUG	0x0001
@@ -888,6 +892,20 @@ struct mta_envelope {
 	char				 status[LINE_MAX];
 };
 
+enum agentx_index_type {
+	AGENTX_INDEX_TYPE_UNDEFINED,
+	AGENTX_INDEX_TYPE_ANY,
+	AGENTX_INDEX_TYPE_NEW,
+	AGENTX_INDEX_TYPE_VALUE,
+};
+
+struct smtp_agentx {
+	const char			*path;
+	const char			*context;
+	enum agentx_index_type		 applIndexType;
+	uint32_t			 applIndex;
+};
+
 struct mta_task {
 	TAILQ_ENTRY(mta_task)		 entry;
 	struct mta_relay		*relay;
@@ -1333,6 +1351,9 @@ void config_peer(enum smtp_proc_type);
 int control(void);
 int control_create_socket(void);
 
+/* control_agentx.c */
+void control_agentx(void);
+void control_agentx_connect(int);
 
 /* crypto.c */
 int	crypto_setup(const char *, size_t);
diff --git a/usr.sbin/smtpd/smtpd/Makefile b/usr.sbin/smtpd/smtpd/Makefile
index 34a4dc74..53853da6 100644
--- a/usr.sbin/smtpd/smtpd/Makefile
+++ b/usr.sbin/smtpd/smtpd/Makefile
@@ -1,4 +1,8 @@
+<<<<<<< HEAD
 #	$OpenBSD: Makefile,v 1.91 2018/06/03 14:04:06 gilles Exp $
+=======
+#	$OpenBSD: Makefile,v 1.108 2020/09/23 18:01:27 martijn Exp $
+>>>>>>> 770825c6930... Add support for agentx to smtpd.
 
 .PATH:		${.CURDIR}/..
 
@@ -11,6 +15,7 @@ SRCS+=	cert.c
 SRCS+=	compress_backend.c
 SRCS+=	config.c
 SRCS+=	control.c
+SRCS+=	control_agentx.c
 SRCS+=	crypto.c
 SRCS+=	dict.c
 SRCS+=	dns.c
@@ -84,8 +89,8 @@ SRCS+=		stat_ramstat.c
 MAN=		sendmail.8 smtpd.8 smtpd.conf.5 table.5
 BINDIR=		/usr/sbin
 
-LDADD+=		-levent -lutil -lssl -lcrypto -lm -lz
-DPADD+=		${LIBEVENT} ${LIBUTIL} ${LIBSSL} ${LIBCRYPTO} ${LIBM} ${LIBZ}
+LDADD+=		-levent -lutil -lssl -lcrypto -lm -lz -lagentx
+DPADD+=		${LIBEVENT} ${LIBUTIL} ${LIBSSL} ${LIBCRYPTO} ${LIBM} ${LIBZ} ${LIBAGENTX}
 
 CFLAGS+=	-fstack-protector-all
 CFLAGS+=	-I${.CURDIR}/..